A robot is a programmable and highly versatile manipulation device. They can be used in mobile or stationary applications and can be employed for various tasks thanks to the freely-programmable movement sequence. Robots are used for various work processes in, for example, industrial assembly or production. Generally speaking, a robot consists of a manipulator (robot arm), which can be moved by means of appropriate drives and a control device. An end effector is usually provided at the end of a robot arm, which end effector can, as a working body, perform various tasks. Measuring devices, screwdrivers, testing devices or even grippers can be used as end effectors, for example. A gripper is a manipulation device, which establishes temporary contact with a gripped object and ensures the position and orientation of the gripped object during the pick-up and set-down operations. The holding of the gripped object is achieved, for example, by means of force-generating, form-fitting or material-matching components.
In order to grip an object to be gripped, a teaching of individual points fixed in space is usually realized. The robot is thus positioned, e.g. manually, such that the gripper is located in an appropriate position at the object to be gripped. After this positioning of the robot, the corresponding pose is stored as a gripping pose. The grip of the robot should be selected such that it can be executed in a collision-free manner and is also solid, so that the object cannot slip or shift in the gripper. Special restrictions must also be considered, since the object may not be able to be gripped at all positions.
This method of individual grip determination has a number of disadvantages. Thus, a successful execution of a fixed-programmed grip requires that the object to be gripped is always located in the same position and, if appropriate, has the same orientation in space. However, this is not always the case in complex working environments where both humans and multiple robots work together. Furthermore, a successful execution of a fixed-programmed grip also requires that the robot is always located at the same position. However, in mobile robotics it is entirely possible for the positioning accuracy of a mobile robot to be inadequate to the task of sufficiently accurately applying a firm grip to a target object. In addition, most objects offer more than just one possible solid grip, but these are not taken into consideration in the above-described method.
The European patent application EP 2 263 837 A1 describes a method, wherein, amongst other things, a primary shape model is adjusted according to 3D-position data of a space, which corresponds to a detection area, which is acquired using a distance measuring device. U.S. Pat. No. 8,355,816 B2, which was published in the English language on Jan. 15, 2013 and corresponds to European patent application EP 2 263 837 A1, is hereby incorporated by reference in its entirety herein.
The patent document EP 2 657 863 A2 describes a method for generating robot grip patterns using a plurality of proximity beams which are associated with an object. U.S. Pat. No. 9,014,857 B2, which was published in the English language on Apr. 21, 2015 and corresponds to European patent document EP 2 657 863 A2, is hereby incorporated by reference in its entirety herein.
These two methods are also relatively complex and permit no intuitive identification of gripping poses by the operator.
Given this technical background, the objective of the present invention is to provide a method and a system, to allow simple and easy determination of possible gripping poses. Gripping poses should preferably be taught directly, using a robot at the actual object. Another objective of the present invention is to provide a method for determining gripping poses at an object and for gripping an object, which eliminates or minimizes the above-mentioned disadvantages. The objective is achieved with the method according to Claim 1 and Claim 11 and with the robot system according to Claim 12.